The captivating blue and orange shades visible in the sky during sunrise and sunset might be crucial in regulating our internal body clocks. Recent research has discovered that a new LED light, emitting alternating blue and orange wavelengths, was more effective than two other lighting devices in increasing melatonin levels among a small group of participants. This discovery could pave the way for a new method to influence human circadian rhythms and may offer a promising treatment for seasonal affective disorder (SAD).
The captivating blue and orange shades visible in the sky during sunrise and sunset might be crucial in regulating our internal body clocks.
According to new findings from the University of Washington in Seattle, the innovative LED light that alternates between orange and blue wavelengths surpassed two other types of lighting in raising melatonin levels among a limited number of study subjects.
Published in the Journal of Biological Rhythms, this study seems to set a new standard for how humans can affect their circadian rhythms and represents a promising strategy to alleviate seasonal affective disorder (SAD).
A range of emotional and physical health issues has been linked to disrupted circadian rhythms, which can be caused by seasonal changes, insufficient natural light, night shifts, and traveling across time zones.
“Our internal clock indicates how our body should function at different times of the day, but it needs to be set correctly; if our brain is not aligned with the time of day, it won’t function properly,” stated Jay Neitz, a coauthor of the study and a professor of ophthalmology at the UW School of Medicine.
Circadian rhythms are adjusted daily by the light and dark cycles that occur every 24 hours, which activate pathways in the eyes that send signals to the brain. Based on this information, the brain generates melatonin, a hormone that promotes sleep aligned with nighttime cycles.
Individuals who spend lots of time in artificial lighting typically exhibit circadian rhythms with delayed melatonin production compared to those who receive more natural light. Many commercial lighting solutions aim to mitigate these delays.
Most of these solutions focus on blue light because it impacts melanopsin, a light-sensitive pigment in our eyes that reacts most strongly to blue wavelengths.
In contrast, Neitz explained, “The light we created does not rely on melanopsin. Instead, it features alternating blue and orange wavelengths that activate a blue-yellow opposing circuit through the cone photoreceptors in the retina. This circuit is notably more receptive than melanopsin and helps our brains reset our internal clocks.”
The lead author of the paper, James Kuchenbecker, a research assistant professor of ophthalmology at the UW School of Medicine, aimed to test and compare the effects of various artificial lighting on melatonin production.
He and his colleagues set up an experiment to test three types of lighting:
- a white light of 500 lux (a brightness suitable for general office environments)
- a short-wavelength blue LED aimed at stimulating melanopsin
- the newly created LED that alternates between blue and orange wavelengths, creating a gentle white light.
The objective was to identify which lighting method would most effectively advance the timing of melatonin production among six participants. Each person followed a structured regimen involving exposure to all three lighting devices:
On the first evening, multiple saliva samples were collected to establish a baseline for the beginning and peak of each participant’s melatonin production. Based on this baseline, each participant was then exposed to the test light for two hours the following morning. Saliva samples were again collected that evening to check if their melatonin phase had advanced relative to their original levels.
All light exposure outside of the tested devices was controlled. The testing times were arranged so that participants could return to their normal melatonin levels before transitioning to a new device.
The alternating blue-orange LED device proved to be the most effective, advancing melatonin production by 1 hour and 20 minutes. The blue light resulted in a 40-minute phase advance, while the 500-lux white light achieved a mere 2.8-minute advance.
Neitz commented on their developed light, saying, “Though it appears white to the eye, we believe the brain recognizes the alternating blue and orange wavelengths similarly to the colors found in the sky. The circuit that produced the most substantial shift in melatonin prefers orange and blue light.”
This research received support from the National Institutes of Health (R01 EY027859, P30EY001730 and T32EY007031).
Collaborating with the UW, Neitz and Kuchenbecker have commercialized this innovative lighting technology, which is now produced and sold by a Chicago-based company named TUO.
